In the prior art of electro-mechanics, accelerometers were used to sense the acceleration of remote targets. Although accelerometers may work satisfactorily at high acceleration rates, they are not accurate at extremely low acceleration rates. Moreover, as the number of measurement points increases, the necessary cables or other data transmission means render the use of accelerometers expensive and unreliable.
Another technique utilized to measure distances to a plurality of points on a surface was to utilize an independent coherent light source and an independent detector for each point to be measured. Another technique was to have a multiplicity of targets and a single coherent light source, which was sequentially aimed at the multiplicity of targets.
The use of an independent coherent light source and an independent detector suffers from high cost and reduced reliability. The sequential measurement technique reduces the cost of a measurement system but still suffers from reduced reliability. Moreover, the sequential measurement technique is slow, and because it can only sense the distance to one point at a time, it cannot accurately measure the distance between two or more points.